Monday, March 9, 2015

OSI Model

Protocol 
A set of rules that govern how something works.
Within a computer science:
  • A communication protocol is a system of digital rules for data exchange within or between computers
  • When data is exchanged through a computer network, the rules system is called a network protocol 
Logical Protocol (SMTP) - It is how emails are sent

  • HTTPS - Browsing through the net 

  • TSP

Physical
  • Bluetooth
  • Wifi
Lowest layer is logical and the highest is physical.


Physical layer = Describes electrical and physical specifications for devices: Cable, connectors, hubs.

Data link layer = Provides connections between hosts on the same network: Ethernet 

Network layer =  Provides connection between hosts on different networks :IPv4 and IPv6. Routing of packets.

Transport = Provides transport of data: TCP and UDP. End to end connections.

Session =  establishing a connection. Controls the dialogs between computers (handshake). Also controls duplexing termination and restarts. 

Presentation = compressing the data.  Provides a context for communication between layers 
ASCII Characters, Encryption and decryption. Compression.

Application = HTTPS, where we find network application eg mail, browser 
  • All
  • People
  • Studying
  • This 
  • Needs
  • Drastic
  • Psychotherapy

It hands communication between computers across networks.

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